Iowa State Research Farm Progress Reports
2012
Organic Practices for the Production of
Muskmelon
Jean C. Batzer
Iowa State University, jbatzer@iastate.edu
Steven Johnson Iowa State University Mark L. Gleason
Iowa State University, mgleason@iastate.edu
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Recommended Citation
Batzer, Jean C.; Johnson, Steven; and Gleason, Mark L., "Organic Practices for the Production of Muskmelon" (2012).Iowa State Research Farm Progress Reports. 38.
Abstract
Cucurbit crops, especially muskmelon and cucumber, attract cucumber beetles, which vector bacterial wilt: Erwinia tracheiphila, causing significant crop losses. High beetle densities are associated with high bacterial wilt incidence, which usually occurs during the first stages of plant establishment. Growers of organic muskmelon need effective ways to manage the cucumber beetle/bacterial wilt complex.
Keywords
RFR A1107, Plant Pathology and Microbiology
Disciplines
Agriculture | Plant Pathology
Iowa State University, Horticulture Research Station ISRF11-36
7
Organic Practices for the Production of Muskmelon
RFR-A1107Jean Batzer, assistant scientist Steven Johnson, undergraduate student Mark Gleason, professor/extension plant
pathologist
Department of Plant Pathology
Introduction
Cucurbit crops, especially muskmelon and cucumber, attract cucumber beetles, which vector bacterial wilt: Erwinia tracheiphila, causing significant crop losses. High beetle densities are associated with high bacterial wilt incidence, which usually occurs during the first stages of plant establishment.
Growers of organic muskmelon need effective ways to manage the cucumber beetle/bacterial wilt complex.
Row covers are usually deployed from transplant until anthesis (start of flowering), then removed to allow insect pollination. Several studies at ISU and elsewhere have suggested that a 10-day delay in row cover removal can shield muskmelon crops from the first emergence of wilt-vectoring cucumber beetles, resulting in much less bacterial wilt, and correspondingly better yield, than either removing the cover at anthesis or not using row covers at all. Opening the ends of the row covers has been tried in order to allow for pollination.
This project is the second year in a three-year multi-state effort, with Kentucky and
Pennsylvania, to optimize organic growing practices that effectively manage insect and diseases, and enhance pollination for cucurbit crops.
Materials and Methods
Transitioning organic land was used for the multi-factorial experimental plot at the ISU Horticulture Research Station, Ames, Iowa.
On May 17, three-week-old organic
transplants of Strike muskmelon were planted 2 ft apart in black plastic mulch with drip irrigation and 8-ft centers. Subplots consisted of 30-ft rows of 15 plants. Spunbond
polypropylene row covers (Agribon® AG-30) were installed on wire hoops immediately after transplanting.
A Latin square experimental design using 16 subplots (4 replicates of 4 treatments) was used to examine impacts of row cover
treatments:
1) No row covers (control).
2) Row covers applied at transplanting and removed at anthesis (start of perfect flower bloom).
3) Row covers applied at transplanting with the ends opened at anthesis and removed 10 days later (Figure 1).
4) Row covers applied at transplanting and removed 10 days after anthesis.
OMRI-registered insecticides and fungicides were applied on a rescue basis only, triggered by results of weekly monitoring. Pyganic® was applied to control picnic beetle damage on ripening fruit, the evening of August 7. Champ 50WG® (copper hydroxide) was used to control anthracnose. Weed management was achieved with 6 in. of corn stalk mulch between rows and composted bark was placed around the opening in the plastic around each seedling before row cover placement.
Striped and spotted cucumber beetle adult numbers were monitored weekly from transplant through the beginning of harvest using yellow sticky cards and weekly counts from five randomly chosen plants. Disease incidence was monitored weekly. Melons were harvested twice weekly to optimize fruit quality for four weeks beginning July 29. The number and weight of marketable and cull
melons harvested from each subplot was recorded.
Results and Discussion
Cucumber beetles did not enter the plot until early July, as evidenced by weekly counts on plants and sticky card captures (Table 1, Figure 2), although cucumber beetles were observed in other cucurbit fields at the
research station in early June. Low frequency of bacterial wilt was detected (11 of 240 plants) fairly late in the growing season (July 21) (Table 1, Figure 3a) and did not affect yield (P>0.05). However, row cover treatments 3 and 4, which delayed removal until ten days after anthesis, had lower
numbers of wilt later in the season (Figure 3a).
Earliness and yield were not enhanced by row covers this season (P>0.05) (Table 1, 3b). In addition to the lack of bacterial wilt, this may have been related to the absence of severe weather early in the growing season where row covers can offer protection to the young transplants. Because first harvest dates for treatment 3 were about one week earlier than for treatment 4, it is likely that pollinators were accessing the flowers under the row covers through the open ends (Figure 1).
Acknowledgements
Thanks to Nick Howell, the ISU Horticulture Farm crew and the 312 Bessey field crew for crop planting, maintenance and harvest.
Table 1. Summary of organic production of muskmelon using row covers.
Row cover treatment
Number of sprays Dates
Weight (lb) per 30-ft plot Pyganic Copper Row covers removed First cuke beetles First bacterial
wilt Marketable Cull*
1. 2.1 No row covers 3. 1 2 NA July 12 July 27 101.2 20.2 2 Row covers removed at anthesis
1 2 June 22 July 12 July 22 100.9 24.4
3 Open ends at anthesis; row covers removed 10 days later
1 2 July 1 July 12 Aug. 3 87.8 20.7
4 Row covers removed 10 days after anthesis
1 2 July 1 July 12 Aug. 3 115.9 20.9
Iowa State University, Horticulture Research Station ISRF11-36 9 0 1 2 3 4 5 6 7
5‐Jul 12‐Jul 19‐Jul 26‐Jul 2‐Aug 9‐Aug
Per cent plants with bacterial wilt no row cover row cover removed at anthesis ends opened at anthesis rc removed 10 d later row cover removed 10 d a@er anthesis
Figure 1. Row cover with open ends allowed pollinators to access flowers (Treatment 3).
Figure 2. Weekly counts of striped and spotted cucumber beetles from sticky card traps in each
plot.
Figure 3. Bacterial wilt incidence (a) and cumulative mean marketable harvest weight (b) from four-row cover treatments.
0 1 2 3 4 5 6
31‐May 7‐Jun 14‐Jun 21‐Jun 28‐Jun 5‐Jul 12‐Jul 19‐Jul 26‐Jul 2‐Aug 9‐Aug
Beetle number
STRIPED SPOTTED
3a